# Testing specific optical rotation of a given sample by using Polarimeter SOPs

Title: Standard operating procedure for testing specific optical rotation of a given sample by using Polarimeter.

1.0                 OBJECTIVE:

To lay down the procedure for testing specific optical rotation of a given sample by using Polarimeter.

2.0                 SCOPE:

This shall be applicable to the Polarimeter of Quality Control Laboratory.

3.0                 RESPONSIBILITY:

3.1  Technical Assistant/ Helper.

3.2  Q.C Analyst.

4.0                 ACCOUNTABILITY:

4.1  Manager-Quality Control.

4.2  Head of the Q.C Department.

5.0                 MATERIAL AND EQUIPMENT:

5.1  Polarimeter.

5.2  Analytical weighing balance.

5.3  Sample solution as specified in monograph.

5.4  Solvent as specified in monograph.

6.0                 PROCEDURE:

6.1  Firstly clean the Polarimeter with clean dry cloth, according to SOP.

6.2  Operate the Polarimeter according to SOP.

6.3  Determine the zero of the Polarimeter and the angle of rotation of polarized light at wavelength of D-line of sodium (λ=589.3nm) at 20±0.5oC, unless otherwise prescribed.

6.4  Measurements may be carried out at other temperatures only where monograph indicates the temperature correction to be made to the measured optical rotation.

6.5  Determine the zero of the apparatus with tube closed; for liquids the zero is determined with tube empty and for solids filled with prescribed solvent.

6.6  Method:

6.6.1  Weigh the sample by using weighing balance, operate it according to SOP.

6.6.2  Prepare the sample solution as specified in monograph by using appropriate solvent quantity.

6.6.3  Fill the Polarimeter tube with blank solution and determine the observed optical rotation.

6.6.4  Similarly, fill the Polarimeter tube with sample solution and determine the observed optical rotation.

6.6.5  Note down the values in annexure 1.

6.7  Calculate the specific optical rotation by using formula:

[α]λ T = α/lc

7.0                 REVISION LOG:

 Revision No. Effective Date Reason 00 New SOP

8.0                 REFERENCES:

8.1  The British Pharmacopoeia. Vol V., Official Monograph / Determination of optical rotation and specific optical rotation: 2015, pp. 244.

9.0                 ANNEXURES:

Annexure 1: Observations and calculations.

Annexure: 1

Observations and calculations

Instrument: ___________________                                              Date: _______________

Model: _______________________        Length of Polarimeter tube: ________________

Sample: ________________________________g.

Solvent: ________________________________ml.

Concentration of sample solution: ____________g/ml.

Blank solution:

 Sr.# Blank solution Temperature Optical rotation (α)

Average: _______________

Optical rotation of blank solution: _______________

Sample solution:

 Sr.# Sample solution Temperature Optical rotation (α)

Average: _______________

Optical rotation of sample solution: ______________

Optical rotation of substance = Blank solution - Sample solution.

Specific optical rotation of sample solution by using formula:

[α]λ T = α/lc

Result: ________________

Remarks: ________________________________________________